I'm trying to mount Luxos IQ2 onto the fork crown. There isn't quite enough space between the back of the light and front brake cable and I was wondering if I could add a spacer between IQ2 metal bracket and the fork crown. Or would it weaken the stability of the mount?
The only problem that you might run into with a spacer is that you'd loose the fit on the curve of the fork, so the light might be little more likely to flop to the side. I would think that a rubber or leather washer would handle that.
You don't need anything as fancy as a purpose built part. Your local hardware store will most likely have box upon box of little bits of odd hardware and among them you can find spacers in various lengths, along with longer bolts if you need them. You might want to get a couple of metal washers as well to provide a solid clamping surface. Or buy the fancy mount…
If I can offer advice where I wasn't asked, you might want to consider mounting the light higher or farther forward. I really don't like the shadow of the front tire that mine casts when it is mounted at the fork crown.